The blue catfish is the largest and one of the most popular freshwater sportfish in Texas and surrounding states, however many established catfish populations are the result of stocking programs. According to statewide stocking records from the Texas Parks and Wildlife Department, more than 10 million catfish have been stocked into Texas reservoirs since 1993. These stockings can result in established fisheries, but many others fail to produce established populations.

A new Baylor University study has identified several key physical, chemical and biological factors that influence the success of blue catfish populations in Texas reservoirs. The study was completed in collaboration with the Texas Parks and Wildlife Department and is the largest and most comprehensive study ever done exploring catfish survivability in Texas.

The study results were presented at the second International Ictalurid Symposium and will appear in Conservation, Ecology and Management of Worldwide Catfish Populations and Habitats by the American Fisheries Society in July 2011.

"Understanding the factors that influence the success of blue catfish populations will help researchers and managers make better informed decisions regarding where, exactly, the best lakes are to stock," said Brian Bartram, a Baylor graduate student who helped lead the study and is a Texas Parks and Wildlife biologist. "These findings confirm what we were seeing in the field and now provide a scientific backing to any future water management plans as they relate to catfish."

 Environmental factors do indeed influence blue catfish populations in Texas. Specifically, surface area of the lake, climate and the amount of nutrients in the lake, such as phosphorus and chlorophyll, have the greatest influence on blue catfish survivability.

 While surface area and nutrient productivity showed the most influence on blue catfish populations, it is the correct combination of the two that seems to provide the optimal conditions for blue catfish to thrive. The combination of high nutrient productivity like phosphorus and chlorophyll, within large reservoirs seemed to provide the optimum reservoir conditions to support blue catfish populations. For example, Lake Corpus Christi performs well in terms of catfish survivability since it is a large lake with high nutrient supply.

 Overall, the reservoirs that showed no evidence of catfish reproduction had relatively very small surface areas, ranging from 166 hectares to 961 hectares. For example, Lake Kurth in east Texas could not sustain a catfish population. The Baylor researchers believe reservoirs with small surface areas have a small geographic footprint, encompassing fewer habitat types and may not provide suitable spawning or food habitats. Previous studies have shown that catfish prefer deep, inundated river channel habitats over coves and shallow water habitats.

 Climate also was a factor in survivability, however it was very loosely correlated. Latitude showed a positive loading, while growing season showed a negative loading on the climate factor, meaning as one moves north, catfish survivability increased. However, the Baylor researchers say this result may simply be a product of geography and reservoir distribution in Texas. There are more reservoirs in the central and northern parts of the total reservoir distribution and most are large, resource filled reservoirs.

"This study suggests that reservoir attributes and environmental variables play a role in the establishment and survival of blue catfish," said Dr. Patrick Danley, assistant professor of biology at Baylor, who helped lead the study. "We can now predict across the entire state which lakes can sustain catfish and which ones struggle."